This invention relates to an arrangement wherein a plurality of body members are positioned in precise relationship on a carrier body, and, more particularly, it relates to an arrangement wherein manipulators position these bodies at elevated temperatures and in an inert gas environment.
The technical problem is one of positioning and bonding a solid body in a specific spatial relation to another object. It is often necessary to position a solid body relative to another object with a high degree of accuracy and to attach it at the respective positioned location in a manner that will provide long term stability, upon achieving this accuracy.
A light beam wave-guide, for example a glass fibre or optical fibre, is to be affixed to a laser diode with a specified separation larger than or equal to zero or to some predetermined value. Through the use of proper optics a light beam wave-guide is to be attached to a laser diode with a specified separation greater than zero, whereby the light emitted by the diode is, for example, to be efficiently coupled by means of the proper optics to the beam wave-guide. A tapered lens arranged at the end of the glass fibre may, for example, be employed as the suitable optics.
During the attachment of a light beam wave-guide to a laser diode with a specified separation, especially during the application of a single mode optical fibre as a beam wave-guide, particularly stringent requirements are posed with regard to the positional accuracy and to the long term stability of this positional accuracy during operating and storage conditions. The positional accuracy of a single mode optical fibre must then have a long term stability with a maximum tolerance of within or .+-.0.05 .mu.m. This maximum tolerance must not be exceeded during operation and storage conditions over the range of -40.degree. C. to +60.degree. C.
With regard to the respective light beam wave-guides employed, either smaller or greater accuracies must be maintained for positioning and bonding the light beam wave-guide in front of the respective laser diode.
In the case of multi-mode optical fibres, for example, in the case of graded index fibres with a cone diameter of 50 .mu.m, a position and long term location tolerance .DELTA.x, .DELTA.y on the order of .+-.1 .mu.m must be maintained. In the application of a single mode optical fibre which may exhibit a core of 5 .mu.m, for example, a position and long term location tolerance .DELTA.x, .DELTA.y on the order .+-.0.05 .mu.m must be maintained.
With presently available mechanical and electro-mechanical adjusting devices, for example, with a stepping motor, with a piezo-crystal etc., the attainment of the previously mentioned adjustment accuracies for short periods, and the retaining of this accuracy for seconds, and even minutes, is relatively free of problems.
It is however impossible, with presently available procedures and devices, to bond the beam wave-guides with the attained accuracy, while maintaining the respective location of the beam wave-guide, after positioning, in the long term.
Previously, a number of different light beam wave-guide bonding methods were, or would be, applied in the construction of laser diode modules. In most of the laser modules on the market today, the laser diode is attached to its own mount assembly which is in turn attached through an intermediate fastening element to a light beam wave-guide bonding point. In this way the light beam wave-guide is either fastened in a capillary made of metal-quartz or similar materials, or directly attached at the point of bonding. The attachment of the light beam wave-guide is thus accomplished through the following different techniques or arrangements.
In one technique, the beam wave-guide is directly cemented to the positioning point. In another technique, the beam wave-guide is cemented into a capillary and the capillary is in turn cemented, soldered, welded etc., at the positioning point. In a third technique, the beam wave-guide is metalized, then soldered into the capillary and the capillary then soldered to the positioning point, etc.
All of these conventional bonding techniques for a light beam wave-guide have to a greater or lesser extent disadvantages of various kinds, as for example:
(I) During cementing of the beam wave-guide to the positioning point, the beam wave-guide must be held in position at the positioning point to an accuracy of .+-.0.05 .mu.m during hardening of the cement, which is practically impossible in the present state of the art.
(II) Too little is as yet known about the long term stability of the various cements.
(III) During the soldering of the beam wave-guide at the bonding point with the assembly techniques employed until now for beam wave-guide module construction, a heat source is necessary for heating the solder, which to a large extent also heats the laser diode, so that operation of the laser diode during the positioning procedure is not possible in most cases, whereby adjustment by coupling to light and optical observation during photo-diode operation is impossible and accurate positioning is made substantially more difficult.
(IV) During welding or soldering of a beam wave-guide mounted in a capillary, a considerable displacement of the beam wave-guide may occur, during the cooling process, especially in the case of welding, that is substantially greater than .+-.0.05 .mu.m.
(V) In all of the light beam wave-guide techniques mentioned in the foregoing, the light beam wave-guide is attached to the mount assembly on which the laser diode is mounted, through intermediate elements, such as through various metals, various materials, screwed and/or soldered and/or cemented. The stability of the beam wave-guide is thereby directly related to the mechanical and thermal behavior characteristics of these intermediate elements, this means, that a displacement or a thermal stress, which must of necessity arise, during temperature cycling between +60.degree. C. and -40.degree. C. with many of the intermediate elements used in the present arrangements of the prior art, are directly carried over into the light beam wave-guide laser coupling and make it practically impossible to maintain long-term stability.